Evaluating the Influence of Polyethylene Glycol Side-Chain Content on the Electrochromic Properties for Diketopyrrolopyrrole-EDOT Copolymers

Description:
Conjugated polymers have become state-of-the-art materials for many organic electronic applications, e.g. photovoltaics (OPV), thin-film transistors (TFT), and electrochromics (EC), due to their relatively low-cost and low-toxicity, desirable mechanical properties, and facile structural and electronic tuning. More recently, their inclusion in mixed ionic-electronic applications, such as electrochromics and organic electrochemical transistors (OECT), has garnered increased interest due to the potential for these soft-materials to be incorporated into various biological settings. A class of copolymers that provide exceptional redox stability and desirable light-absorption properties are those based on diketopyrrolopyrrole (DPP) and 3,4-ethylenedioxithiophene (EDOT). We have recently shown that DPP-copolymers can provide exceptional performance (transconductance up to 30.75 S/cm) and mechanical properties (strain up to 140%) in OECTs. However, the copolymer structure could still be further optimized via the inclusion of polyethylene glycol (PEG) sidechains on the DPP unit to further facilitate electrolyte penetration and ion transport. In this work we probe the effect of PEG sidechain content on the electrochemical and electrochromic properties for a series of DPP-EDOT copolymers by varying the structural composition and PEG-sidechain content. Extensive electrochemical and spectroelectrochemical characterization is performed with variation in the identity of the electrolyte in aqueous and organic solvents. Additionally, the morphology and microstructure of the films are extensively characterized using GIXRD and AFM. This research was supported by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at Northwestern University administered by Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy and the Office of the Director of National Intelligence (ODNI).

Speaker: Robert Pankow - Northwestern University
Robert Pankow is currently an Intelligence Community (IC) Postdoctoral Fellow in Prof. Tobin Marks Group in the Department of Chemistry at Northwestern University. He earned his Ph.D. in Chemistry from the University of Southern California (2020) under the guidance of Prof. Barry C. Thompson where he developed more sustainable conditions for conjugated polymer synthesis and studied their performance in polymer solar cells and other organic electronic applications. Before this he earned his BA in Chemistry from UC Santa Barbara (2012) and MS in Chemistry from CSU Northridge (2015). His current research interests include the design and synthesis of functional organic materials, developing more sustainable polymerization conditions, and organic electronics.